Lazy 1-2 and 2-3 Shifts

[AndyL]

On my 99 (with the heath reflash ECM which includes a "shift kit") the shifts are lazy, 3-4 and lockup feel firm. I have had a recent flush with filter and the fluid looks great.

Any ideas?

[Kennedy]

IMHO, a REAL shift kit is a valuable asset in these trucks. Transgo 4L80EHD2 I believe is the one that I use. No substitute for drilling holes, filling holes etc.

A program can add line psi, but it can't overcome mechanical restrictions in the transmission...

[AndyL]

Since 3-4 is Firm is it possible I have an internal problem? Could a shift solonoid cause this?

[Kennedy]

Hard to speculate over the net, but first thing I'd be looking at is how it shifts with stock ECM.

I've said it before, the OE 99 programming is tough to beat. Hearing those claiming pedal response is aggressive leads me to believe that the linear progression of the APP may have been altered, giving more power with less pedal which may be messing with not only shift firmness, but shift points. The firm 3-4 may be a product of TCC being locked up, OR the TCC locking up.

For a quick test, you could try the Auto Trans interceptor module to dial up some more psi.

[Turbine Doc]

Shift kit plus reflash is the way to go, I have B&M kit plus the reflash very crisp shifts in all gears, I ran the 99 OEM it was definately an improvement over my 98, but the Heath 2.0 reflash was the ticket.

Better shifts, but biggest gain was fuel & boost not clipping back boost is almost linear with APP, more APP, more boost more grins from passengers "This is a Diesel???" is a common question.

Andy make sure you have latest revision night & day difference between early & latest, as I have a kit + reflsh I don't know how to advise you, do you have a tranny guy you are in good with have him run the diagnostics on it, with a T2 or Snap on scanner if something is amiss and the tranny shop is good should be easy to find a problem.

Or now might be a good time to think about a trans filt change, a deep pan www.yourcovers.com (http://www.yourcovers.com) and a shift kit JK may have one.

I got mine from Summit with my trans cooler; B&M technical folks said a shift kit was better than a module, especially if you are into the trans already, if still not happy then add the moidule, but they can set codes.

[damork]

AndyL
I've been running the BD Race chip in mine since about 50,000 miles and now approaching 190,000. The shifts have been firmer than the oem chip, but like JK says the true way to correct shifts is with hardware.

I don't have a kit in mine yet, and although I have high miles, I believe regular fluid changes and keeping it cool have been a big help. Check out www.sonnax.com (http://www.sonnax.com) and www.transgo.com (http://www.transgo.com) - lots of options out there. WWW.bulkpart.com (http://WWW.bulkpart.com) is a good source for the hardware as well.

TransGo, Sonnax, and Superior all make parts for these transmissions to improve shifts / make improvements. Lately the Sonnax products have been coming on strong in the transmission aftermarket from what rebuilders have told me. I've looked at some of their hardware and it is very well designed.

Many builders agree the 4L80E should have a boost valve update done regardless how old it is as a stuck one will ruin the case. Sonnax makes a lot of kits to fix worn valve body bores as well as shift improvers.

You might want to check your pressures as a starting point as well as ensuring you are getting full voltage to the power line into the transmission. I added a relay for mine to reduce the ignition switch load, and make a habit to check grounds from time to time.